Title of Invention	METHODS AND APPARATUSES FOR CDMA2000/GPRS ROAMING
Abstract	Interworking and interoperability function IIF architectures and corresponding call flows are provided for CDMA2000/GPRS roaming scenarios such as GPRS foreign mode with Mobile IPv4, GPRS foreign mode with Simple IPv4 or IPv6, CDMA2000 packet data foreign mode with Mobile IPv4, and CDMA2000 packet data foreign mode with Simple IPv4 or IPv6.

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FORM 2 THE PATENTS ACT, 1970 (39 of 1970) & THE PATENTS RULES, 2003 COMPLETE SPECIFICATION (See section 10, rule 13) "METHODS AND APPARATUSES FOR CDMA2000/GPRS ROAMING" QUALCOMM Incorporated, a corporation under the laws of state Delaware of United States of America of 5775 Morehouse Drive, San Diego, California 92121-1714, United States of America The following specification particularly describes the invention and the manner in which it is to be performed. WO 2005/057980 2- 2 PCT/US2004/040430 METHODS AND APPARATUSES FOR CDMA2000/GPRS ROAMING Claim of Priority under 35 U.S.C. §119 [0001] The present Application for Patent claims priority to Provisional Application No. 60/526,557 entitled "CDMA/GPRS Packet Data Roaming" filed December 3,2003, and assigned to the assignee hereof and hereby expressly incorporated by reference herein. BACKGROUND Field [0002] The present disclosed embodiments relate generally to wireless communications, and more specifically to roaming in the context of CDMA2000 and GPRS systems. Background |0003] Wireless subscribers may desire to use their wireless terminals in conjunction with wireless systems other man their home systems to obtain access to services using their existing subscriptions. Access to these services may be independent of men-normal wireless terminals, through wireless systems other than their home systems. This may occur, for example, when the subscriber is roaming outside the service area of men-home system. Accordingly, manufacturers and system operators desire to allow subscribers to receive services using their terminals and subscriptions via a system which may not be the subscriber's home system, provided that the terminal and the serving system are compatible. [0004] Serving roaming subscribers can be difficult even when the serving system and home system employ identical technologies. When the serving system uses an air interface that differs from that used in the subscriber's home system, interworking between these systems is typically performed due to fundamental differences in message protocols, call models, et cetra. This interworking can be achieved via an Interworking and Interoperability Function (IIF). [0005] One example of an IIF is described in US Patent Application 2002/094811 Al to Bright et al. entitled "Interworking and Interoperability of GPRS Systems With Systems of Other Technology Families." US Patent Application 2002/094811 Al provides a WO 2005/057980 3 PCT/US2004/040430 GPRS interworking and interoperability function (DF) interposed between a serving GSM/GPRS wireless system and a second wireless system of a different technology family. The IIF allows a mobile station homed to the second wireless system to operate in the GSM/GPRS system. According to US Patent Application 2002/094811 Al, telecommunications system components are provided that allow interworking and interoperability of a serving GSM and/or GPRS system with certain "domestic wireless" systems. For example, a mobile station homed on such a domestic wireless system, but registered with the serving system in a GPRS-only mode, may receive services from the serving system. US Patent Application 2002/094811 Al mentions that the term "domestic wireless" (DW) is intended to refer to non-GSM systems compatible with ANSI or equivalent standards for TDMA, CDMA, and analog cellular systems, as generally used in North America, or compatible with other similar systems. [0006] Although US Patent Application 2002/094811 A1 acknowledges the need for an TIF allows a mobile station homed to a CDMA wireless system to operate in the GSM/GPRS system, US Patent Application 2002/094811 A1 does not discuss an HF adapted for CDMA2000/GPRS roaming scenarios when the terminal is using Mobile IP or Simple IP. US Patent Application 2002/094811 A1 fails to provide sufficient information, direction or guidance regarding how an IIF could be constructed mat would allow a mobile station homed to a CDMA2000 wireless system could operate in the GSM/GPRS system, when the terminal is using Mobile IP or Simple IP. For example, US Patent Application 2002/094811 A1 fails to provide any details regarding what modules would be needed to implement such an IIF, how the modules would be interconnected, timed and controlled so as to obtain the specific operations needed to implement such an IIF. [0007] Thus, there is a need in the art for a general architecture can be adapted for CDMA2000/GPRS roaming scenarios, such as, GPRS foreign mode with Mobile IPv4, GPRS foreign mode with Simple IPv4 or IPv6, CDMA2000 packet data foreign mode with Mobile IPv4, and CDMA2000 packet data foreign mode with Simple IP, Mobile IPv4 or Mobile IPv6. It would be desirable to enable communication between a CDMA 2000 packet data system and a GPRS system, when a CDMA 2000 packet data native subscriber using Simple IP, Mobile IPv4 or Mobile IPv6 roams to the GPRS system by supporting bearer connectivity between the GPRS and CDMA 2000 packet data system. Similarly, it would also be desirable to enable communication between a GPRS system WO 2005/057980 4 PCT/US2004/040430 and a CDMA 2000 packet data system when a GPRS native subscriber roams from the GPRS system to the CDMA 2000 packet data system using Simple IP, Mobile IPv4 or Mobile IPv6 by supporting bearer connectivity between the GPRS system and the CDMA 2000 packet data system. SUMMARY [0008] According to one aspect of the invention, an interface entity, interposed between a CDMA 2000 packet data system and a GPRS system, is provided that enables communication between the CDMA 2000 packet data system and the GPRS system when a CDMA 2000 packet data native subscriber roams to the GPRS system by supporting bearer connectivity between the GPRS and CDMA 2000 packet data system by providing a packet routing function. [0009] According to one aspect of the invention, an interface entity is provided that enables communication between a home CDMA 2000 packet data system and a visited GPRS system comprising a SGSN, when a CDMA 2000 packet data native subscriber using Mobile IPv4 roams to a visited GPRS system. [0010] For example, in an embodiment where a CDMA 2000 packet data native subscriber roams to a visited system and uses Mobile IPv4, an interface entity can be provided mat couples the home system to the visited system to enable communication between the home system and the visited system, hi this situation, the home system is a CDMA 2000 packet data system that can include a ANSI-41 home location register; an AAA entity; and a home agent, whereas the visited system can be a GPRS system that includes a SGSN. [0011] According to one aspect of this embodiment, the interface comprises a GSM home location register emulation module, and an ANSI-41 visited location register emulation module. The GSM home location register emulation module can be coupled to the SGSN via a Gr interface, that allows a subscriber to register over a Gr interface, whereas the ANSI-41 visited location register emulation module can be coupled to the ANSI-41 home location register via a D interface that allows a subscriber to register over the D interface. According to one aspect of this embodiment, the interface further comprises a foreign agent emulation module and a GGSN emulation module. The foreign agent emulation module can be coupled to the home agent via an XI interface, and supports bearer connectivity between the visited system and the home system such WO 2005/057980 5 PCT/US2004/040430 that a foreign agent interface and an AAA interface are presented to the CDMA 2000 packet data system over the XI interface. The GGSN emulation module can be coupled to the SGSN via a Gp interface, and can support bearer connectivity between the visited system and the home system such that a GGSN interface is presented to the visited system over the Gp interface. The interface can serve as an endpoint for a GTP tunnel and a Mobile IP tunnel. In this embodiment, the interface provides a packet routing function between the GGSN interface and the foreign agent interface. According to another aspect of this embodiment, the interface can also include an AAA emulation module that can be coupled to the AAA entity via an X3 interface. In this embodiment, the AAA emulation module provides an accounting function to interacting with a home network's AAA for Mobile IP Foreign Agent challenge authentication and 3GPP2 packet data accounting. [0012] According to one aspect of the invention, an interface entity is provided mat enables communication between a home CDMA 2000 packet data system and a visited GPRS system comprising a SGSN, when a CDMA 2000 packet data native subscriber using Simple IP roams to a visited GPRS system. [0013] man embodiment where a CDMA 2000 packet data native subscriber roams to a visited system and uses Simple IP, an interface entity can be provided that couples the home system to the visited system to enable communication between the home system and the visited system. In this situation, the home system is a CDMA 2000 packet data system that can include a ANSI-41 home location register; an AAA entity; and a LNS, whereas the visited system can be a GPRS system that includes a SGSN. [0014] According to one aspect of this embodiment, the interface comprises an ANSI- 41 visited location register, and a GSM home location register. The ANSI-41 visited location register can be coupled to the ANSI-41 home location register via a D interface, and allows a subscriber to register over the D interface. The GSM home location register can be coupled to the SGSN via a Gr interface and allows a subscriber to register over the Gr interface. According to another aspect of this embodiment, the interface may comprise a LAC emulation module and a GGSN emulation module. The LAC emulation module can be coupled to the LNS via an X2 interface, and supports bearer connectivity between the visited and home networks over the X2 interface. The GGSN emulation module can be coupled to the SGSN via a Gp interface, and supports bearer connectivity between the visited and home networks over the Gp interface by WO 2005/057980 6 PCT/US2004/040430 presenting a GGSN interface to the visited system and presenting a normal routing interface to the CDMA 2000 packet data system to thereby provide a packet routing function between the GGSN interface and the home system. In this case, the interface serves as an endpoint for a GTP tunnel and an IPSec tunnel. According to yet another aspect of this embodiment, the interface can include an AAA emulation module mat can be coupled to the AAA entity via an X3 interface. The AAA emulation module can provide an accounting function by interacting with the home network's AAA for L2TP authentication and 3GPP2 packet data accounting over the X3 interface. [0015] According to another aspect of the invention, an interface entity, interposed between a GPRS system to a CDMA 2000 packet data system, is provided that enables communication between the GPRS system and the CDMA 2000 packet data system when a GPRS native subscriber roams from the GPRS system to a CDMA 2000 packet data system using one of Mobile IPv4 and Simple IP by supporting bearer connectivity between the GPRS system and the CDMA 2000 packet data system by providing a packet routing function. [1016] According to yet another aspect of the invention, an interface entity is provided that enables communication between a home GPRS system comprising a GSM home location register, a GGSN, and an AAA entity, and a visited CDMA 2000 packet data system that comprises an ANSI-41 visited location register, an AAA entity, and a packet data serving node/ foreign agent, when a GPRS native subscriber using Mobile IPv4 roams to the visited CDMA 2000 packet data system. [0017] In an embodiment where a GPRS native subscriber roams to a visited system and uses Mobile IPv4, an interface entity can be provided that couples the home system to the visited system to enable communication between the home system and the visited system. In this situation, the home system is a GPRS system comprising a GSM home location register, a GGSN; and an AAA entity, whereas the visited system can comprise a CDMA 2000 packet data system that includes a ANSI-41 visited location register; a AAA entity, and a packet data serving node/ foreign agent [0018] According to one aspect of this embodiment, the interface comprises a home agent emulation module and a SGSN emulation module. The home agent emulation module can be coupled to the packet data serving node/ foreign agent via an XI interface, and presents a home agent interface to the visited system. The SGSN emulation module can be coupled to the GGSN via a Gp interface, and presents a SGSN WO 2005/057980 7 PCT/US2004/040430 interface to the home system to support bearer connectivity between the visited and home networks by providing a packet routing function between the SGSN interface and the home agent interface. Here, the interface serves as an endpoint for a GTP tunnel and a Mobile IP tunnel. According to another aspect of this embodiment, the interface can also include an ANSI-41 home location register emulation module, and a GSM visited location register emulation module. The ANSI-41 home location register emulation module can be coupled to the ANSI-41 visited location register via a D interface, whereas the GSM visited location register emulation module can be coupled to the GSM home location register via a D interface, to allow a subscriber to register. According to yet another aspect of this embodiment, the interface may also include an AAA emulation module that can be coupled to the AAA entity via a Gi interface and coupled to the AAA entity via a X3 interface. The AAA emulation module interacts with the visited network's AAA for Mobile IP authentication and 3GPP2 packet data accounting, over the X3 interface, and the home network's AAA for 3GPP packet data accounting, over the Gi interface. [0019] According to one aspect of the invention, an interface entity is provided mat enables communication between a home GPRS system comprising a GSM home location register, a GGSN, and an AAA entity, and a visited CDMA 2000 packet data system that comprises an ANSI-41 visited location register, an AAA entity, and a packet data serving node/LAC entity, when a GPRS native subscriber using Simple IP roams to the visited CDMA 2000 packet data system. [0020] In an embodiment where a GPRS native subscriber roams to a visited system and uses Simple IP, an interface entity can be provided that couples the home system to the visited system to enable communication between the home system and the visited system. In this situation, the home system is a GPRS system comprising a GSM home location register; a GGSN; and an AAA entity, whereas the visited system can comprise a CDMA 2000 packet data system that includes a ANSI-41 visited location register, a AAA entity; and a packet data serving node/LAC entity. According to one aspect of the invention, the interface supports bearer connectivity between the visited and home networks by providing a packet routing function. For example, the interface can include a SGSN emulation module, and a LNS emulation module. The SGSN emulation module can be coupled to the GGSN over a Gp interface, and presents a SGSN interface to the home system, whereas the LNS emulation module can be coupled to the packet WO 2005/057980 8 PCI7US2004/040430 data serving node/ LAC entity over an X2 interface, and presents a L2TP Network Server (LNS) interface to the visited system. As such, this interface provides the packet routing function between the SGSN emulation module and the LNS emulation module. Here, the interface serves as an endpoint for a GTP tunnel and a Mobile L2TP tunnel. [0021] According to another aspect of this embodiment, the interface comprises a ANSI-41 home location register emulation module and a GSM visited location register emulation module. The ANSI-41 home location register emulation module can be coupled to the ANSI-41 visited location register via a D interface, whereas the GSM visited location register emulation module can be coupled to the GSM home location register via another D interface. This allows a subscriber to register. According to yet another aspect of this embodiment, the interface may also include an AAA emulation module mat can be coupled to the AAA entity via a Y3 interface and coupled to the AAA entity via a X3 interface. The AAA emulation module interacts with the visited network's AAA entity, over an X3 interface, for L2TP authentication and 3GPP2 packet data accounting, and with the home network's AAA entity, over an Gi interface, for 3GPP packet data accounting. BRIEF DESCRIPTION OF THE DRAWINGS [0022] FIG. 1 is a block diagram of a system that comprises a home system, a visited system, and an interface entity that enables communication between the home system and the visited system; (0023] FIG. 2A is a block diagram of GPRS foreign mode with Mobile IPv4; [0024] FIG. 2B is a call flow diagram that shows Mobile IPv4 operation in the GPRS foreign mode; [0025] FIG. 3 A is a block diagram of GPRS foreign mode with Simple IP; [0026] FIG. 3B is a call flow diagram that shows Simple IP operation in the GPRS foreign mode; [0027] FIG. 4A is a block diagram of CDMA2000 packet data foreign mode with Mobile IPv4; [0028] FIG. 4B is a call flow diagram that shows Mobile IPv4 operation in the CDMA2000 packet data foreign mode; [0029] FIG. 5A is a block diagram of CDMA2000 packet data foreign mode with Simple IP; and WO 2005/057980 9 PCT/US2004/040430 [0030] FIG. 5B is a call flow diagram that shows Simple IP operation in the CDMA2000 packet data foreign mode. DETAILED DESCRIPTION [0031] The word "exemplary” can be used herein to mean "serving as an example, instance, or illustration." Any embodiment described herein as "exemplary" can be not necessarily to be construed as preferred or advantageous over other embodiments. [0032] FIG. 1 is a block diagram of a system that comprises a home system 10, such as a CDMA 2000 packet data system or a GPRS system, a visited system 20, such as a GPRS system or a CDMA 2000 packet data system, and an interface entity 30 or "HF" that couples the home system 10 to the visited system 20, and enables communication between the home system 10 and the visited system 20. 10033] The following sections describe architectures that can be adapted for CDMA2000/GPRS roaming scenarios, such as, GPRS foreign mode with Mobile IPv4, GPRS foreign mode with Simple IPv4 or IPv6, CDMA2000 packet data foreign mode with Mobile IPv4, and CDMA2000 packet data foreign mode with Simple IPv4 or IPv6. GPRS Foreign Mode with Mobile IPv4 [0034] FIG. 2A is an exemplary block diagram of a GPRS foreign mode with Mobile IPv4, and depicts the functions and control interface provided by an IIF in this embodiment This roaming scenario occurs when a CDMA2000 packet data native subscriber operates Mobile IPv4 [IS-835-C] in GPRS foreign mode. In this embodiment, the home system 10 can be a CDMA 2000 packet data system wherein a CDMA 2000 packet data native subscriber roams to a GPRS system and uses Mobile IPv4. The home system 10 comprises a ANSI-41 home location register 131, an AAA entity 116, and a home agent 135. The visited system 20 can be a GPRS system mat comprises a SGSN 137. [0035] The interface 30 or "IIF” comprises an ANSI-41 visited location register 111 coupled to the ANSI-41 home location register 131 via a D interface 113, a GSM home location register 124 coupled to the SGSN 137 via a Gr interface 123, a GGSN 126 coupled to the SGSN 137 via a Gp interface 127 and coupled to the Internet via a Gi interface, an AAA entity 140 coupled to the AAA entity 116 via an X3 interface 117, and a foreign agent 118 coupled to the home agent 135 via an XI interface 115. The IIF WO 2005/057980 10 PCT7US2004/040430 provides both GSM HLR and ANSI-41 VLR emulation to allow the subscriber to register. This interworking can be provided over the interface references "Gr" and "D". The IDF provides GGSN and FA emulation to support bearer connectivity between the visited and home networks via the DF. This interworking can be provided over the interface references "Gn" and "XI". The ITJF provides AAA emulation to interact with the home network's AAA for Mobile IP Foreign Agent challenge authentication and 3GPP2 packet data accounting. This interworking can be provided over the interface reference "X3". [0036] If bearer connectivity between from the GPRS system and the CDMA2000 packet data system is not required, then reverse tunneling on the XI interface is not required. Rather, MS-terminated traffic traverses through the XI and Gp interfaces. In the case where reverse tunneling is not required, the IIF routes MS-originated traffic, received on a Gp interface, to the Internet directly via a Gi interface. [0037] Thus, for a user homed in a CDMA Mobile IP system roaming to a GSM system, the KF may present a GGSN interface to GSM and a FA and AAA interfaces to the CDMA system. The DF may serve as the endpoint for the GTP and Mobile IP tunnels, with a packet routing function between the GGSN and FA. The DF may also provide an accounting function so mat operators can charge based on configurable measurements such as packet count, bandwidth, time of day, etc. [0038] FIG. 2B is an exemplary call flow diagram that shows Mobile IPv4 operation in the GPRS foreign mode. FIG. 2B depicts a call flow example for the roaming scenario where a CDMA2000 packet data native subscriber operates Mobile IPv4 [IS-835-C] in the GPRS foreign mode. In this example, the MS has shared secrets with the home CDMA2000 system for Mobile IP authentication. The MS may request the home CDMA2000 system to assign a HA and/or an IP address. The reverse tunneling can be enabled so that all data traffic (MS-originated and -terminated) traverses through the DF and home CDMA2000 system. The ID? generates 3GPP2 packet data accounting records and sends it to the home CDMA2000 system via RADIUS. [0039] The MS performs GPRS attach with a SGSN. The authentication associated with the GPRS attach can be a SIM-based authentication requiring the Ki secret key. The IIF acts as the GSM HLR configured with the Ki secret. In any case, the IIF can be not required to communicate with the HLR in the home CDMA2000 system for the authentication. (Step 1) The MS sends the Activate PDP Context Request to the WO 2005/0579*0 11 PCT/US2004/040430 SGSN. The message includes the Access Point Name (APN). The APN has the format ...gprs. The Network ID (e.g., CDMA2000carrier.com) indicates to which external network the MS wants to establish a logical connection. The Requested PDP Address can be omitted in the message. The MS has a static Mobile IP home address or obtains a new Mobile IP home address. (Step 2) The SGSN selects a GGSN based on the APN. The SGSN uses the APN as the lookup name to query a DNS server (not shown in the figure) and obtains a list of available GGSNs that can be used to support the requested APN. The APN's Network ID indicates a CDMA2000 operator, thus, the DNS server returns with the IIFs IP address. (Step 3) The SGSN sends the Activate PDP Context Request to the selected HF to set up a PDP context for the MS. The message includes the APN, but the Requested PDP Address can be omitted. (Step 4) The ID? acts as the GGSN and sends the Create PDP Context Response to the SGSN that in turn sends the Activate PDP Context Accept to the MS. The PDP Address in both messages can be set to 0.0.0.0 to indicate that the PDP address will be assigned later after successful Mobile IP registration. (Step 5) The EOF acts as the FA and sends one or more Mobile IP Agent Advertisements to the MS, because the omission of the Requested PDP Address in the Activate PDP Context Request can be the indication that the MS wishes to use Mobile IP. The Agent Advertisement can be sent over the established PDP context The Agent Advertisement contains the FA Care-of Address and the FA Challenge (FAQ. (Step 6) [0040] The MS sends the Mobile IP Registration Request to the IIF over the PDP context. The following information can be contained in the Registration Request: MS's NAI [RFC 2794] has the format of @, where the domainname identifies the MS's home CDMA2000 system. MS-HA authenticator can be computed based on the content of the Registration Request and the secret shared between the MS and HA [RFC 2002]. MS-AAA authenticator can be computed based on the FAC and the secret shared between the MS and home AAA server [RFC 3012]. The HA Address field can be set to a known value if the MS uses a permanent HA, or to 0.0.0.0 if the MS wants a new HA assigned by the home network. Home Address field can be set to a known value if the MS uses a permanent address, or to 0.0.0.0 if the MS wants a new address assigned by the HA. The T-bit can be set to one to enable a reverse tunnel from the IIF to the MS's HA. (Step 7) The ID? acts as the RADRJS client and sends a RADRIS Access-Request to the home AAA server. The RADRJS Access- WO 2005/057980 12 PCT/US2004/040430 Request conveys MS's NAI, FAC authenticator, FAC, HA address, etc. [IS-835]. (Step 8) If the authentication is successful, the home AAA server responds with the RADIUS Access-Accept that includes the MS's HA address. (Step 9) The HF acts as the FA and forwards the Mobile IP Registration Request to the HA address contained in the RADIUS Access-Accept. (Step 10) The HA verifies the MS-HA authenticator in the Mobile IP Registration Request If the HA doesn't have the shared secret, as in the case of dynamically assigned HA, it communicates with the home AAA server for the shared secret. The HA responds to the Mobile IP Registration Request with the Mobile IP Registration Reply containing a registration result (e.g., successful or an error code). If the MS wishes for a new home address, a new address can be returned in the Registration Reply, otherwise, the MS's permanent address can be returned. (Step 11) The TIF acts as the FA and forwards the Mobile IP Registration Reply to the MS over the appropriate PDP context The ID? FA functionality notes the assigned MS IP address and shares that address with the EOF GGSN functionality. (Step 12) [0041] The IIF acts as the GGSN and updates its PDP context by setting the PDP address to the MS' s home address (as indicated in the Registration Reply and shared by the FA functionality). The PDP address (hence the MS's home address) can be associated with a GTP tunnel identified by the Tunnel Endpoint ID (TEID). (Step 13) The HF acts as the GGSN and triggers the GGSN-initiated PDP Context modification procedure in order to update the PDP address in the SGSN and MS [3GPP TS 29.061]. The HF sends the Update PDP Context Request to the SGSN that forwards it to the MS. (Step 14) The MS responds with the Update PDP Context Response to the SGSN mat forwards it to the UF. (Step 15) The HF acts as the RADIUS client and sends the RADIUS Accounting-Request (Start) to the home AAA server [IS-835]. 3GPP2-vendor-specific attributes are used to convey accounting records, but some airlink record attributes (e.g., service option, mux option, etc.) are not applicable. (Step 16) The home AAA server responds with a RADPJS Accounting-Response (Start). (Step 17) Bearer traffic traverses through the ID? in both directions, if reverse tunneling from the HF to HA is enabled. For routing MS-originated packets, the HF routes packets received from the MS's GTP tunnel (identified by a TEID) to the MS's HA via a Mobile IP reverse tunnel. For routing MS-terminated packets, the ID? routes packets received from the HA-to-FA tunnel to the MS's GTP tunnel. IPsec can be used to WO 2005/057980 13 PCT/US2004/040430 protect the Mobile IP tunnels between HA and EOF, and the GTP tunnels between IIF and SGSN. (Step 18) GPRS Foreign Mode with Simple IP [0042] FIG. 3 A is an exemplary block diagram of a GPRS foreign mode with Simple IP that shows a roaming scenario where a CDMA2000 packet data native subscriber operates IPv4 or IPv6 in the GPRS foreign mode. FIG. 3A also depicts the functions and control interface provided by an interface or IIF in this case, hi this embodiment, the home system 10 can be a CDMA 2000 packet data system wherein a CDMA 2000 packet data native subscriber roams to a GPRS system and uses Simple IP. The home system 10 comprises a ANSI-41 home location register 131, an AAA entity 116, and a LNS 139. The visited system 20 can be a GPRS system that comprises a SGSN 137. [0043] The interface 30 or "IIF" comprises an ANSI-41 visited location register 111 coupled to the ANSI-41 home location register 131 via a D interface 113, a GSM home location register 124 coupled to the SGSN 137 via a Gr interface 123, a GGSN 126 coupled to the SGSN 137 via a Gp interface 127 and coupled to the Internet via a Gi interface, an AAA entity 140 coupled to the AAA entity 116 via an X3 interface 117, and a LAC entity 109 coupled to the LNS 139 via an X2 interface 119. The HF provides both GSM HLR and ANSI-41 VLR emulation to allow the subscriber to register. This interworking can be provided over the interface references "Gr" and "D." The IIF provides GGSN and LAC emulation to support bearer connectivity between the visited and home networks via the IIF. This interworking can be provided over the interface references "Gn" and "X2." The IIF provides AAA emulation to interact with the home network's AAA for L2TP authentication and 3GPP2 packet data accounting. This interworking can be provided over the interface reference "X3." [0044] If bearer connectivity between the CDMA2000 packet data system and GPRS system is not required, then the X2 interface is not required. The IIF still supports a Gp interface to the SGSN and provides Internet access via a Gi interface (not shown in the figure). [0045] Thus, for a user homed in a CDMA Simple IP system roaming to a GSM system, the IIF may present a GGSN interface to GSM and a normal routing interface to the CDMA system. The ITF may serve as the endpoint for the GTP and IPSec tunnels, with a packet routing function between the GGSN and the CDMA system. The HF may WO 2005/057980 14 PCTAJS2004/040430 also provide an accounting function so that operators can charge based on configurable measurements such as packet count, bandwidth, time of day, etc. [0046] FIG. 3B is an exemplary call flow diagram that shows Simple IP operation in the GPRS foreign mode, and explains a roaming scenario where a CDMA2000 packet data native subscriber operates Simple IP in the GPRS foreign mode. In this example, the MS has shared secrets with the home CDMA2000 system for Simple IP authentication (i.e., CHAP). The MS establishes a PPP session, via LOT, to the home CDMA2000 system. During the PPP establishment, the home CDMA2000 system assigns an IP address to the MS dynamically. All the MS's data traffic (MS-originated and - MS terminated) traverses through the IIF and home CDMA2000 system. The IIF generates 3GPP2 packet data accounting records and sends it to the home CDMA2000 system via RADIUS. [0047] The MS performs GPRS attach with a SGSN. The authentication associated with the GPRS attach can be a SIM-based authentication requiring the Ki secret The IIF acts as the GSM HLR configured with the Ki secret or the GSM VLR In any case, the OF can be not required to communicate with the HLR in the home GDMA2000 system for the authentication. (Step 1) The MS sends the Activate PDP Context Request to the SGSN. The message includes me APN (Access Point Name). The APN has me format ...gprs. The Network ID (e.g., CDMA2000carrier.com) indicates to which external network the MS wants to establish a logical connection. The Requested PDP Address can be omitted in the message so that the IIF (acting as a GGSN) later will not assign an IP address to the MS; instead, the address will be assigned by the LNS. (Step 2) The SGSN selects a GGSN based on the APN. The SGSN queries a DNS server (not shown in the figure) and obtains a list of available GGSNs that can be used to support the requested APN. hi this case, the APN*s Network ID indicates a CDMA2000 operator, thus, the DNS server returns with the IIF's IP address- (Step 3) [0048] The SGSN sends the Activate PDP Context Request to the selected IIF to set up a PDP context for the MS. The message includes the APN, but the Requested PDP Address can be omitted. (Step 4) The DF acts as the GGSN and sends the Create PDP Context Response to the SGSN that in turn sends the Activate PDP Context Accept to the MS. The PDP Address in both messages can be set to 0.0.0.0 to indicate that the PDP address will be reset later. (Step 5) WO 2005/057980 15 PCT/US2004/040430 - [0049] After the PDP context can be established, the MS and IIF perform PPP LCP negotiation. The IDF LAC functionality establishes L2TP tunnels with a LNS. The IIF determines which LNS based on the requested APN. The IIF is configured with the LNS information (e.g., LNS's IP address) corresponding to an APN. After the L2TP tunnel establishment, the IIF LAC functionality forwards LCP information between the LNS and MS. During the LCP negotiation, the LNS and MS negotiate PAP or CHAP as the protocol for PPP authentication. (Step 6) PPP authentication (PAP or CHAP) is performed. The MS's credential is authenticated by the home AAA in the CDMA2000 system. The RADIUS interaction between the LNS and home AAA is not shown in the figure. (Step 7) The LNS and MS perform PPP TPCP negotiation. The IIF LAC functionality relays IPCP messages between the L2TP tunnel and PDP context. During the negotiation, the LNS assigns an IP address to the MS. The IIF monitors for this address and uses it as the MS's PDP address. (Step 8) [0050] The IIF also needs to notify the SGSN and MS about the updated PDP address. Recall that the PDP address can be set to 0.0.0.0 initially. Therefore, the TIF sends the Update PDP Context Request to the SGSN that forwards it to the MS. (Step 9) The MS responds with the Update PDP Context Response to the SGSN that forwards it to the TIF. (Step 10) [0051] The HF acts as the RADIUS client and sends the RADIUS Accounting-Request (Start) to the home AAA server [IS-835]. 3GPP2-vendor-specific attributes are used to convey accounting records, but some airlink record attributes (e.g., service option, mux option, etc.) are not applicable. (Step 11) The home AAA server responds with the RADIUS Accounting-Response (Start). (Step 12) Bearer traffic traverses through the ITF in both directions. For routing MS-originated packets, the ITF routes packets received from the MS's GTP tunnel (identified by a TEID) to the MS's L2TP tunnel/session. For routing MS-terminated packets, the HF routes packets received from the MS's L2TP tunnel/session to the MS's GTP tunnel. IPsec can be used to protect the L2TP tunnel/session between LNS and ITF, and the GTP tunnels between IDF and SGSN. (Step 13) CDMA2000 Packet Data Foreign Mode with Mobile IPv4 [0052] FIG. 4A is an exemplary block diagram of a CDMA2000 packet data foreign mode with Mobile IPv4. This section describes the roaming scenario where a GPRS WO 2005/057980 16 PCT/US2004/040430 native subscriber operates Mobile IPv4 jTS-835-C] in the CDMA2000 packet data foreign mode. FIG. 4A also depicts the functions and control interface provided by the IIF in this case. In this embodiment, the home system 10 can be a GPRS system. A GPRS native subscriber roams to a CDMA 2000 packet data system and uses Simple IP. The home system 10 comprises a GSM home location register 124, a GGSN 126, and an AAA entity 128. The visited system 20 can be a CDMA 2000 packet data system that comprises a ANSI-41 visited location register 111, an AAA entity 116, and a packet data serving node/ foreign agent 118. [0053] The interface 30 or "IIF' comprises an ANSI-41 home location register 131 coupled to the ANSI-41 visited location register 111 via a D interface 113, a GSM visited location register 133 coupled to the GSM home location register 124 via a D interface 121, a SGSN 137 coupled to the GGSN 126 via a Gp interface 127, an AAA entity 140 coupled to the AAA entity 128 via a X4 interface 129 and coupled to the AAA entity 116 via a X3 interface 117, and a home agent 135 coupled to the packet data serving node/ foreign agent 118 via a XI interface 115. The HF provides both GSM VLR and ANSI-41 HLR emulation to allow the subscriber to register. This interworking can be provided over the interface reference "D". The IIF provides HA and SGSN emulation to support bearer connectivity between the visited and home networks via the HF. This interworking can be provided over the interface reference "XI" and "Gn". The HF provides AAA emulation to interact with the visited network's AAA for Mobile IP authentication and 3GPP2 packet data accounting. The IIF also may interact with the home network's AAA for 3GPP packet data accounting. This interworking can be provided over the interface reference "X3" and "X4". The EOF/AAA requirements for CDMA2000 packet data foreign mode with mobile IP will be described below in greater detail. [0054] If bearer connectivity between the visited GDMA2000 packet data system and home GPRS system is not required, the Gp interface is not required. In this case, mobile-originated data traffic can be routed directly to the Internet via the PDSN/FA in the visited system, or via the DDF/HA if reverse tunneling is enabled. Mobile-terminated data traffic is routed to the PDSN/FA via the IIF/HA. The interface X3 and X4 are required for the IIF to interwork AAA messages between the CDMA2000 AAA server and GPRS AAA server. WO 2005/05798© \*| PCT/US2004/04043© [0055] Thus, for a user homed m a GSM system roaming to a CDMA Mobile IP system, the DF may present a HA interface to the CDMA system and a SGSN interface to the GSM system. A subset of SGSN functions is required including APN resolution. The EOF may serve as the endpoint for the Mobile IP and GTP tunnels, with a packet routing function between the HA and SGSN functions. [0056] FIG. 4B is an exemplary call flow diagram that shows Mobile IPv4 operation in the CDMA2000 packet data foreign mode. This call flow example shows a roaming scenario where a GPRS native subscriber operates Mobile IPv4 [IS-835-C] in the CDMA2000 packet data foreign mode. In this example, the home GPRS system doesn't support HA; thus, the MS has shared secrets with the DF for Mobile IP authentication. The home GPRS system dynamically assigns an IP address to the MS. All MS's data traffic (MS-originated and MS-terminated) traverses through the HF and home GPRS system. The DF receives 3GPP2 accounting records from the visited CDMA2000 system and may map them to 3GPP accounting records and forward them to the home GPRS system via RADIUS. [0057] The MS originates SO 33 and establishes a PPP session with the PDSN/FA. (Step 1) The PDSN/FA sends one or more Mobile IP Agent Advertisement to the MS, because the omission of the IP-Address Configuration Option daring the PPP IPCP negotiation indicates (hat the MS wishes to use Mobile IP. The Agent Advertisement contains the FA Care-of Address and the FA Challenge (FAC). (Step 2) [0058] The MS sends the Mobile IP Registration Request to the PDSN/FA. The following information can be contained in the Registration Request: MS's NAI [RFC 2794] has the format of @, where the domainname identifies the MS's home GPRS system. MS-HA authenticator can be computed based on the content of the Registration Request and the secret shared between the MS and HA [RFC 2002]. MS-AAA authenticator can be computed based on the FAC and the secret shared between the MS and home AAA server [RFC 3012]. The HA Address field can be set to a known value if the MS uses a permanent HA, or to 0.0.0.0 if the MS wants a new HA assigned by the home network. The HA field can be set to 0.0.0.0 to request a new address assigned by the HA. The T-bit can be set to one to request the PDSN/FA to establish a reverse tunnel to the MS's HA. (Step 3) [0059] The PDSN/FA generates a RADIUS Access-Request conveying MS's NAI, FAC authenticator, FAC, HA address, etc. [IS-835]. Because the domain name of the WO 2005/057980 18 PCT/US2004/040430 MS's NAI indicates a GPRS system, the PDSN/FA sends a RADIUS Access-Request to the IIF via the AAA in the CDMA2000 system. The IIF may modify the message in accordance with [3GPP TS 29.061]. (Step 4) If the authentication is successfull, the home AAA server responds with the RADIUS Access-Accept. The message is routed back to the PDSN via IIF and visited AAA. The IIF may modify the message in accordance with [P.S0001-A V3.0]. (Step 5) The PDSN/FA forwards the Mobile IP Registration Request to the HA function in the HF. The HF verifies the MS-HA authenticator in the Mobile IP Registration Request (Step 6) [0060] If the authentication is successful, the IDF SGSN functionality establishes GTP tunnels with a GGSN in the home GPRS system and can request an IP address from the GGSN. The HF SGSN functionality derives an APN that has the format ID>mnc.mnc.gprs [TS 23.003]. The is the realm portion of the MS's NAI and indicates which GGSN the MS wants to access for the requested service. The and are derived from the MS's IMSI. The MS's NAI and IMSI are available from the RADIUS Access-Request in step 4. The SGSN functionality uses the derived APN as the lookup name to query GPRS DNS server (not shown in the figure) and from it obtains a list of available GGSNs that can be used to support the requested service. The IIF SGSN functionality sends the Create PDP Context Request to the selected GGSN. The Requested PDP Address in the message is set to 0.0.0.0 to request a new IP address. (Step 7) The GGSN responds with the Create PDP Context Response including the new IP address assigned to the MS. (Step 8) The HF acts as the HA and sends the Mobile IP Registration Reply to the MS via the PDSN/FA. The Home Address field in the Mobile IP Registration Reply can be set to the IP address assigned by the GGSN. (Step 9) The PDSN sends the RADIUS Accounting-Request (Start) containing 3GPP2 packet data accounting information [P.S0001-A V3.0]. Because the domain name of the MS's NAI indicates a GPRS system, the RADIUS Accounting-Request (Start) is routed to the home AAA in the GPRS system via the visited AAA and HF. The HF may modify the message in accordance with [3GPP TS 29.061]. (Step 10) The HF acts as the RADIUS server and replies with the RADIUS Accounting-Response (Start). (Step 11) [0061] Bearer traffic traverses through the HF in both directions. For routing MS- originated packets, the HF routes packets received from the Mobile IP reverse tunnel to the MS's GTP tunnel (identified by a TEID). For routing MS-terminated packets, the WO 2005/057980 19 PCT/US2004/040430 IIF routes packets received from the GTP tunnel to a HA-to-FA tunnel. IPsec can be used to protect the Mobile IP tunnels between PDSN/FA and IIF, and the GTP tunnels between IIF and GGSN. (Step 12) IIF/AAA Requirements for CDMA2000 Packet Data Foreign Mode with Mobile IP [0062] The IIF requirements to process the RADIUS Access-Request received from the visited CDMA2000 packet data system will now be described. [0063] The IIF proxies all IETF RADIUS attributes without modification, except the Calling-Station-ID attribute, Called-Station-ID attribute, and Framed-Protocol attribute. The processing of these three attributes is described below. If the Calling-Station-ID attribute in the received RADIUS Access-Request contains IMSI, the HF copies the IMSI into the 3GPP-IMSI attribute [3GPP TS 29.061] and include it in the RADIUS Access-Request destined for the MS's home GPRS system. The TJDF does not include the Calling-Station-ID attribute in the RADRJS Access-Request sent to the home AAA in the GPRS system. If the Calling-Station-ID attribute in the received RADIUS Access-Request contains MIN or IRM, the IIF maps it to the MS's IMSI used in the home GPRS system and include it in the 3GPP-IMSI attribute of the RADIUS Access-Request destined for the home GPRS system. The IIF does not include the Calling-Station-ID attribute in the RADIUS Access-Request sent to the home AAA in the GPRS system. [0064] The IIF includes the Called-Station-ID attribute in the RADIUS Access-Request destined for the MS's home GPRS system. The Value field of the Called-Station-ID attribute is set to the APN (see section 83.4). If the Framed-Protocol attribute is included in the received RADIUS Access-Request, the IIF overrides the value to 7 [3GPP TS 29.061]. The IIF removes all 3GPP2 VSAs from the received RADIUS Access-Request. The IIF is not required to include any 3GPP VSAs, except the 3GPP-IMSI attribute, in the transmitted RADRJS Access-Request destined for the MS's home GPRS system. [0065] The IDF requirements to process the RADRJS Access-Accept received from the MS's home GPRS system will now be described. WO 2005/057980 20 PCT/US2004/040430 [0066] The UF proxies all IETF RADIUS attributes without modification. The HF removes all 3GPP VSAs from the received RADIUS Access-Accept, before transmitting the RADRJS Access-Accept to the visited CDMA2000 packet data system. [0067] If the policy of the home GPRS system requires the roaming MS's data traffic to traverse through the home GPRS system via the DF, and the HA-Address VSA was included in the corresponding RADIUS Access-Request received earlier from the visited CDMA2000 packet data system, the ITF includes the Reverse-Tunnel-Specification VSA in the transmitted RADRJS Access-Accept destined for the visited CDMA2000 packet data system. The value field of the VSA is set to 1 indicating that reverse tunneling is required. [0068] The IIF requirements to process the RADIUS Accounting-Request START and Accounting-Request INTERIM are the same as the requirements to process the RADIUS Access-Request [0069] The IDF requirements to process the RADRJS Accounting-Request STOP are the same as the requirements to process the RADRJS Access-Request with the following additional requirements: If the Session-continue VSA is set to FALSE in the received RADIUS Accounting-Request STOP, and if the ITF has not previously received an Accounting-Request (Start) from another PDSN with the same IP Address (for the case of inter-PDSN handoff with Mobile IP), the IIF inserts the 3GPP-Session-Stop-mdicator VSA to indicate that the PDP session has been terminated. CDMA2000 Packet Data Foreign Mode wife Simple IP [0070] FIG. 5A is an exemplary block diagram of a CDMA2000 packet data foreign mode with Simple IP. This section describes the roaming scenario where a GPRS native subscriber operates IPv4 or IPv6 in the CDMA2000 packet data foreign mode. FIG. 5 A also depicts the functions and control interface provided by the interface 30 or 'TIF' in this case. In this embodiment, the home system 10 can be a GPRS system wherein a GPRS native subscriber roams to a CDMA 2000 packet data system and uses Mobile IPv4. The home system 10 comprises a GSM home location register 124, a GGSN 126, and an AAA entity 128. The visited system 20 can be a CDMA 2000 packet data system that comprises a ANSI-41 visited location register 111, an AAA entity 116, and a home system 109. WO 2005/057580 2| PCTAJS2004/040430 [0071] The interface 30 or "HF" comprises an ANSI-41 home location register 131 coupled to the ANSI-41 visited location register 111 via a D interface 113, a GSM visited location register 133 coupled to the GSM home location register 124 via a D interface 121, a SGSN 137 coupled to the GGSN 126 via a Gp interface 127, an AAA entity 140 coupled to the AAA entity 128 via a X4 interface 129 and coupled to the AAA entity 116 via a X3 interface 117, and a LCS entity 139 coupled to the packet data serving node/ LAC entity 109 via an X2 interface 119. The IIF provides both GSM VLR and ANSI-41 HLR emulation to allow the subscriber to register. This interworking can be provided over the interface reference "D". The IIF provides LNS and SGSN emulation to support bearer connectivity between the visited and home networks via the IIF. This interworking can be provided over the interface reference "X2" and "Gn". The IIF provides AAA emulation to interact with the visited network's AAA for L2TP authentication and 3GPP2 packet data accounting. The HF also may interact with the home network's AAA for 3GPP packet data accounting. This interworking can be provided over the interface reference "X3" and "X4". The HF/AAA requirements for CDMA2000 packet data foreign mode with Simple IP will be described below in greater detail [0072] If bearer connectivity between the visited CDMA2000 packet data system and home GPRS system is not required, the X2 and Gp interface are not required. In this case, both mobile-originated and mobile-terminated data traffic is routed to/from the Internet via the PDSN in the visited system. The interface X3 and X4 are required for the HF to interwork AAA messages between the CDMA2000 AAA server and GPRS AAA server. [0073] Thus, for a user homed in a GSM system roaming to a CDMA Simple IP system, the HF may present a L2TP Network Server (LNS) interface to the CDMA system and a SGSN interface to the GSM system. A subset of SGSN functions is required including APN resolution. The HF may serve as the endpoint for the Mobile L2TP and GTP tunnels, with a packet routing function between the LNS and SGSN functions. [0074] FIG. 5B is an exemplary call flow diagram that shows Simple IP operation in the CDMA2000 packet data foreign mode. This call flow example illustrates a roaming scenario where a GPRS native subscriber operates Simple IP in the CDMA2000 packet data foreign mode. In this example, the MS has shared secrets with the home AAA in WO 2005/057980 22 PCT/US2004/040430 the GPRS system for CHAP authentication. The home GPRS system dynamically assigns an IP address to the MS. All MS's data traffic (MS-originated and mobile- terminated) traverses through the EOF and home GPRS system. The IIF receives 3GPP2 accounting records from the visited CDMA2000 system and maps it to 3GPP accounting records and forward it to the home GPRS system via RADIUS. [0075] The MS originates SO 33 and initiates PPP LCP negotiation with the PDSN/LAC. CHAP can be negotiated as the protocol for PPP authentication. (Step 1) PDSN/LAC sends a CHAP challenge to the MS. (Step 2) The MS replies with its NAI and a challenge response computed based on the challenge and the secret shared with the home AAA in the GPRS system. The PDSN/LAC sends RADIUS Access-Request. Because the domain name of the MS's NAI indicates a GPRS system, the RADIUS Access-Request can be routed through the visited AAA and DP that proxies the message to the home AAA in the GPRS system. The DF may modify the message in accordance with [3GPP TS 29.061]. (Step 3) If the authentication is successful, the home AAA responds with the RADIUS Access-Accept The message can be routed back to the PDSN/LAC via the DP and visited AAA. The IIF inserts the Tunnel-Server-Endpoint attribute in the RADIUS Access-Accept. This attribute informs the PDSN/LAC to establish a L2TP tunnel with the DP that acts as the LNS. The PDSN/LAC sends the CHAP Success to inform the MS about the successful authentication. (Step 4) [0076] The PDSN/LAC establishes a L2TP tunnel/session with the DP that acts as the LNS. During the L2TP tunnel/session establishment, the PDSN/LAC forwards the LCP information (exchanged between the MS and PDSN/LAC) to the DP. The DP LNS functionality may initiate CHAP challenge (not shown in the figure) to authenticate the MS before IPCP negotiation. (Step 5) The DP SGSN functionality establishes GTP tunnels with a GGSN in the home GPRS system and can request an IP address from the GGSN. The DP derives an APN that has the format mnc.mcc.gprs. The is the realm portion of the MS's NAI and is used to indicate which GGSN the MS wants to access for the requested service. The and are derived from the MS's IMSL The MS's NAI and DMSI are available from the RADIUS Access-Request in step 3. The DP SGSN functionality uses the derived APN as the lookup name to query GPRS DNS server (not shown in the figure) and obtains a list of available GGSNs that can be used to support the requested service. The DP SGSN functionality sends the Create PDP WO 2005/057980 23 PCT/US2004/040430 Context Request to the selected GGSN. The Requested PDP Address in the message is set to 0.0.0.0 to request a new IP address. (Step 6) The GGSN responds with the Create PDP Context Response including the new IP address assigned to the MS. (Step 7) [0077] This new IP address can be assigned to the MS during the PPPIPCP negotiation between the IIF and MS. (Step 8) The PDSN/FA sends the RADIUS Accounting-Request (Start) containing 3GPP2 packet data accounting information [IS-835]. The PDSN sends the RADIUS Accounting-Request (Start) containing 3GPP2 packet data accounting information [P.S0001-A V3.0]. Because the domain name of the MS's NAI indicates a GPRS system, the RADRJS Accounting-Request (Start) is routed to the home AAA in the GPRS system via the visited AAA and DF. The HF may modify the message in accordance with [3GPP TS 29.061]. (Step 9) The home AAA replies with the RADIUS Accounting-Response (Start) that is routed back to the PDSN via EOF and visited AAA. (Step 10) [0078] Bearer traffic traverses through the IIF in both directions. For routing MS- originated packets, the IIF routes packets received from the MS's L2TP tunnel/session to the MS's GTP tunnel (identified by a TEID). For rouing MS-terminated packets, the IIF routes packets received from the MS's GTP tunnel to the MS's L2Tptunnel/session IPsec can be used to protect the L2TP tunnel/session between PDSN/LAC and HF, and me GTP tunnels between IIF and GGSN. (Step 11) BF/AAA Requirements for CDMA2000 Packet Data Foreign Mode with Simple IP [0079] The EOF requirements to process the RADIUS Access-Request are the same as the requirements to process the RADIUS Access-Request for the CDMA2000 Packet Data Foreign Mode with Mobile IP, described above. [0080] The EOF requirements to process the RADIUS Access-Accept are similar to the requirements for processing the RADIUS Access-Accept for the CDMA2000 Packet Data Foreign Mode with Mobile IP, however, if the policy of the home GPRS system requires the roaming MS's data traffic to traverse through the home GPRS system v the DQP, and the HA-Address VSA was not included in the corresponding RADIUS Access-Request received earlier from the visited CDMA2000 packet data system, HF inserts the Tunnel-Server-Endpoint, Tunnel-Type, and Tunnel-Medium-" attributes in the transmitted RADIUS Access-Accept destined for the v WO 2005/057980 24 PCT/US2004/040430 CDMA2000 packet data system. The Tunnel-Server-Endpoint attribute indicates the IIF/LNS address. The Tunnel-Type attribute indicates L2TP. The Tunnel-Medium-Type attribute indicate IPv4. [0081] The IIF requirements to process the RADIUS Accounting-Request START and Accounting-Request INTERIM are the same as the requirements to process the RADIUS Accounting-Request START and Accounting-Request INTERIM for the CDMA2000 Packet Data Foreign Mode wife Mobile IP, described above. [0082] The IIF requirements to process the RADIUS Accounting-Request STOP are the substantially the same as the requirements to process the RADIUS Accounting-Request STOP for the CDMA2000 Packet Data Foreign Mode with Mobile IP, however, if the Session-Continue VSA is set to FALSE in the received RADIUS Accounting-Request STOP, and the IP-Technology VSA indicates Simple IP, the IIF inserts the 3GPP-Session-Stop-Indicator VSA to indicate that the PDP session has been terminated. [0083] Those of skill in the art would understand mat information and signals may be represented using any of a variety of different technologies and techniques. For example, data, instructions, commands, information, signals, bits, symbols, and chips mat may be referenced throughout the above description may be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof. [0084] Those of skill would further appreciate that the various illustrative logical blocks, modules, circuits, and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware, computer software, or combinations of both. To clearly illustrate this interchangeability of hardware and software, various illustrative components, blocks, modules, circuits, and steps have been described above generally in terms of their functionality. Whether such functionality can be implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present invention. [0085] The various illustrative logical blocks, modules, and circuits described in connection with the embodiments disclosed herein may be implemented or performed with a general purpose processor, a digital signal processor (DSP), an application WO 2005/057980 25 PCT/US2004/040430 specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general purpose processor may be a microprocessor, but in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration. [0086] The steps of a method or algorithm described in connection with the embodiments disclosed herein may be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. A software module may reside in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in me art An exemplary storage medium can be coupled to the processor such the processor can read information from, and write information to, the storage medium, m the alternative, the storage medium may be integral to the processor. The processor and the storage medium may reside in an ASIC. The ASIC may reside in a user terminal. In the alternative, the processor and the storage medium may reside as discrete components in a user terminal. [0087] The previous description of the disclosed embodiments can be provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention can be not intended to be limited to the embodiments shown herein but can be to be accorded the widest scope consistent with the principles and novel features disclosed herein. [0088] WHAT IS CLAIMED IS: WO 2005/057980 26 PCT/US2004/040430 CLAIMS 1. A method in which a CDMA 2000 packet data native subscriber using Mobile IPv4 roams from a home CDMA 2000 packet data system to a visited GPRS system comprising a SGSN, comprising: coupling the home system to the visited system to enable communication between the home system and the visited system, wherein the home CDMA 2000 packet data system comprises a ANSI-41 home location register, an AAA entity, and a home agent 2. A method according to claim 1, wherein the home CDMA 2000 packet data system comprises a ANSI-41 home location register, an AAA entity, and a home agent, further comprising: allowing a subscriber to register over a first interface; and allowing the subscriber to register over a second interface. 3. A method according to claim 1, further comprising: supporting bearer connectivity between the visited system and the home system such that a foreign agent interface and an AAA interface are presented to the CDMA 2000 packet data system over a third interface; and supporting bearer connectivity between the visited system and the home system such that a GGSN interface is presented to the visited system over a fourth interface. 4. A method according to claim 3, further comprising: providing an endpoint for a GTP tunnel and a Mobile IP tunnel. 5. A method according to claim 4, further comprising: providing a packet routing function between the GGSN interface and a foreign agent interface. 6. A method according to claim 1, further comprising: providing an accounting function by interacting with a home network's AAA for Mobile IP Foreign Agent challenge authentication and 3GPP2 packet data accounting. WO 2005/057980 27 PCT/US2004/04043© 7. A method in which a CDMA 2000 packet data native subscriber using Simple IP roams from a home CDMA 2000 packet data system to a visited GPRS system comprising a SGSN, comprising: coupling the home system to the visited system to enable communication between the home system and the visited system, wherein the home CDMA 2O00 packet data system comprises a ANSI-41 home location register; an AAA entity, and a LNS. 8. A method according to claim 7, further comprising: allowing a subscriber to register over a first interface; and allowing the subscriber to register over a second interface. 9. A method according to claim 8, further compromising: supporting bearer connectivity between the visited and home networks over a third interface; and supporting bearer connectivity between the visited and home networks over a fourth interface by presenting a GGSN interface to the visited system and presenting a normal routing interface to the CDMA 2000 packet data system to thereby provide a packet routing function between the GGSN interface and the home system. 10. A method according to claim 9, further comprising: providing an endpoint for a GTP tunnel and an IPSec tunnel. 11. A method according to claim 10, further comprising: providing an accounting function by interacting with the home network's AAA for L2TP authentication and 3GPP2 packet data accounting over a fifth interface. 12. A method in which a GPRS native subscriber using Mobile IPv4 roams from a home GPRS system to a visited CDMA 2000 packet data system that comprises an ANSI-41 visited location register, an AAA entity, and a packet data serving node/ foreign agent, comprising: WO 2005/057980 28 PCT/US2004/040430 coupling the home system to the visited system to enable communication between the home system and the visited system, wherein the home GPRS system comprises a GSM home location register, a GGSN, and an AAA entity. 13. A method according to claim 12, further comprising: presenting a home agent interface to the visited system; and presenting a SGSN interface to the home system to support bearer connectivity between the visited and home networks by providing a packet routing function between the SGSN interface and the home agent interface. 14. A method according to claim 13, further comprising: providing endpoints for a GTP tunnel and a Mobile IP tunnel. 15. A method according to claim 13, further comprising: allowing a subscriber to register. 16. A method according to claim 15, farther comprising: interacting with the visited network's AAA for Mobile IP authentication and 3GPP2 packet data accounting over a fifth interface; and interacting with the home network's AAA for 3GPP packet data accounting over a fourth interface. 17. A method in which a GPRS native subscriber using Simple IP roams from home GPRS system to a visited CDMA 2000 packet data system that comprises a ANSI-41 visited location register, a AAA entity, and a PDSN/LAC entity, comprising: coupling the home system to the visited system to enable communication between the home system and the visited system, wherein the home GPRS system comprises a GSM home location register, a GGSN, and an AAA entity. 18. A method according to claim 17, further comprising: WO 2005/057980 29 PCT/US2004/040430 supporting bearer connectivity between the visited and home networks by providing a packet routing function. 19. A method according to claim 18, further comprising: presenting a SGSN interface to the home system; presenting a L2TP Network Server (LNS) interface to the visited system; and providing the packet routing function between a SGSN emulation module and a LNS emulation module. 20. A method according to claim 19, further comprising: providing endpoints for a GTP tunnel and a Mobile L2TP tunnel. 21. A method according to claim 20, further comprising: allowing a subscriber to register. 22. A method according to claim 21, further comprising: interacting with the visited network's AAA entity, over an fifth interface, for L2TP authentication and 3GPP2 packet data accounting; and interacting with the home network's AAA entity, over an sixth interface, for 3GPP packet data accounting. 23. A method that enables communication between a home CDMA 2000 packet data system and a visited GPRS system comprising a SGSN, when a CDMA 2000 packet data native subscriber using Mobile IPv4 roams to a visited GPRS system, comprising: allowing a subscriber to register over a first interface that couples a GSM home location register emulation module to the SGSN; and allowing the subscriber to register over a second interface that couples an ANSI-41 visited location register emulation module to a ANSI-41 home location register. 24. A method according to claim 23, wherein the home CDMA 2000 packet data interface entity comprises a ANSI-41 home location register, an AAA entity, and a home agent. WO 2005/057980 30 PCT/US2004/040430 25. A method according to claim 23, further comprising: coupling the home agent to a foreign agent emulation module via a third interface, wherein the foreign agent emulation module supports bearer connectivity between the visited interface entity and the home interface entity such that a foreign agent interface and an AAA interface are presented to the CDMA 2000 packet data interface entity over the third interface; and coupling a GGSN emulation module to the SGSN via a fourth interface, wherein the GGSN emulation module supports bearer connectivity between the visited interface entity and the home interface entity such that a GGSN interface is presented to the visited interface entity over the fourth interface. 26. A method according to claim 25, farther comprising: providing endpoints for a GTP tunnel and a Mobile IP tunnel 27. A method according to claim 26, further compromising: providing a packet Touting function between the GGSN interface and the foreign agent interface. 28. A method according to claim 23, further comprising: coupling an AAA emulation module to the AAA entity via an fifth interface, wherein the AAA emumlation module provides an accounting function by interacting with a home network's AAA for Mobile IP Foreign Agent challenge authentication and 3GPP2 packet data accounting. 29. A method that enables communication between a home CDMA 2000 packet data system and a visited GPRS system comprising a SGSN, when a CDMA 2000 packet data native subscriber using Simple IP roams to a visited GPRS system, wherein the home CDMA 2000 packet data system comprises a ANSI-41 home location register, an AAA entity, and a LNS, comprising: WO 2005/057980 31 PCT/US2004/040430 coupling an ANSI-41 visited location register to the ANSI-41 home location register via a first interface, wherein the ANSI-41 visited location register allows a subscriber to register over the first interface; and coupling a GSM home location register to the SGSN via a second interface, wherein the GSM home location register allows a subscriber to register over the second interface. 30. A method according to claim 29, further comprising: coupling a LAC emulation module to the LNS via an third interface, wherein the LAC emulation module supports bearer connectivity between the visited and home networks over the third interface; and coupling a GGSN emulation module to the SGSN via a fourth interface, wherein the GGSN emulation module supports bearer connectivity between the visited and home networks over the fourth interface by: presenting a GGSN interface to the visited system; and presenting a normal routing interface to the CDMA 2000 packet data system to thereby provide a packet routing function between the GGSN interface and the home system. 31. A method according to claim 29, farther comprising: providing endpoints for a GTP tunnel and an IPSec tunnel. 32. A method according to claim 31, further comprising: coupling an AAA emulation module to the AAA entity via a fifth interface, wherein the AAA emulation module provides an accounting function by: interacting with the home network's AAA for L2TP authentication and 3GPP2 packet data accounting over the fifth interface. 33. A method that enables communication between a home GPRS system comprising a GSM home location register, a GGSN, and an AAA entity; and a visited CDMA 2000 packet data system that comprises an ANSI-41 visited location register, an AAA entity, and a packet data serving node/ foreign agent, when a GPRS native WO 2005/057980 32 PCT/US2004/040430 subscriber using Mobile IPv4 roams to the visited CDMA 2000 packet data system, comprising: coupling a home agent emulation module to the packet data serving node/ foreign agent via a first interface, wherein the home agent emulation module presents a home agent interface to the visited system; and coupling a SGSN emulation module to the GGSN via a second interface, wherein the SGSN emulation module presents a SGSN interface to the home system to support bearer connectivity between the visited and home networks by providing a packet routing function between the SGSN interface and the home agent interface. 34. A method according to claim 33, further comprising: providing endpoints for a GTP tunnel and a Mobile IP tunnel. 35. A method according to claim 33, further comprising: coupling a ANSI-41 home location register emulation module to the ANSI-41 visited location register via a third interface; and coupling a GSM visited location register emulation module to the GSM home location register via a third interface to allow a subscriber to register. 36. A method according to claim 35, further comprising: coupling a AAA emulation module to the AAA entity via a fourth interface and to the AAA entity via a fifth interface, wherein the AAA emulation module interacts with: the visited network's AAA for Mobile IP authentication and 3GPP2 packet data accounting, over the fifth interface, and the borne network's AAA for 3GPP packet data accounting, over the fourth interface. 37. A method that enables communication between a home GPRS system comprising a GSM home location register, a GGSN, and an AAA entity, and a visited CDMA 2000 packet data system that comprises an ANSI-41 visited location register, an AAA entity, and a packet data serving node/LAC entity, when a GPRS native WO 2005/057980 33 PCT/US2004/040430 subscriber using Simple IP roams to the visited CDMA 2000 packet data system, comprising: coupling a SGSN emulation module to the GGSN over a first interface, wherein the SGSN emulation module presents a SGSN interface to the home system; and coupling a LNS emulation module to the packet data serving node/ LAC entity over a second interface, wherein the LNS emulation module presents a L2TP Network Server (LNS) interface to the visited system, wherein the interface provides the packet routing function between the SGSN emulation module and the LNS emulation module. 38. A method according to claim 37, wherein bearer connectivity is supported between the visited and home networks by providing a packet routing function. 39. A method according to claim 38, further comprising: providing endpoints for a GTP tunnel and a Mobile L2TP tunnel 40. A method according to claim 38, further comprising: coupling a ANSI-41 home location register emulation module to the ANSI-41 visited location register via a third interface, wherein the ANSI-41 home location register emulation module allows a subscriber to register; and coupling a GSM visited location register emulation module to the GSM home location register via another third interface, wherein the GSM visited location register emulation module allows the subscriber to register. 41. A method according to claim 40, further comprising: coupling an AAA emulation module to the AAA entity via a fourth interface and coupled to the AAA entity via a fifth interface, wherein the AAA emulation module interacts with: the visited network's AAA entity, over an fifth interface, for L2TP authentication and 3GPP2 packet data accounting, and the home network's AAA entity, over an sixth interface, for 3GPP packet data accounting. WO 2095/957980 34 PCT/US2004/040430 42. A system in which a CDMA 2000 packet data native subscriber using Mobile IPv4 roams to a visited GPRS system comprising a SGSN, comprising: a home CDMA 2000 packet data system comprising a ANSI-41 home location register, an AAA entity, and a home agent; and an interface entity that couples the home system to the visited system to enable communication between the home system and the visited system. 43. A system according to claim 42, wherein the home CDMA 2000 packet data system comprises a ANSI-41 home location register, an AAA entity, and a home agent, and wherein the interlace entity further comprises: a GSM home location register emulation module, coupled to the SGSN via a first interface, that allows a subscriber to register over a first interface; and an ANSI-41 visited location register emulation module, coupled to the ANSI-41 home location register via a second interface, that allows a subscriber to register over the second interface. 44. A system according to claims 42, wherein comprises: a foreign agent emulation module, coupled to the home agent via an third interface, that supports bearer connectivity between the visited system and the home system such that a foreign agent interface and an AAA interface are presented to the CDMA 2000 packet data system over the third interface; and a GGSN emulation module, coupled to the SGSN via a fourth interface, that supports bearer connectivity between the visited system and the home system such that a GGSN interface is presented to the visited system over the fourth interface. 45. A system according to claim 44, wherein the interface entity serves as an endpoint for a GTP tunnel and a Mobile IP tunnel. 46. A system according to claim 45, wherein the interface entity provides a packet routing function between the GGSN interface and the foreign agent interface. WO 2005/057980 PCT/US2004/040430 35 47. A system according to claim 42, wherein the interface entity further comprises: an AAA emulation module, coupled to the AAA entity via an fifth interface, that provides an accounting function by to interacting with a home network's AAA for Mobile IP Foreign Agent challenge authentication and 3GPP2 packet data accounting. 48. A system in which a CDMA 2000 packet data native subscriber using Simple IP roams to a visited GPRS system comprising a SGSN, comprising: a home CDMA 2000 packet data system that comprises: a ANSI-41 home location register; an AAA entity; and a LNS; and an interface entity that couples the home system to the visited system to enable communication between the home system and the visited system. 49. A system according to claim 48, wherein the interface earthy further comprises: an ANSI-41 visited location register, coupled to the ANSI-41 home location register via a first interface, mat allows a subscriber to register over the first interface; and a GSM home location register, coupled to the SGSN via a second interface, that allows a subscriber to register over the second interface. 50. A system according to claim 49, wherein the interface entity further comprises: a LAC emulation module, coupled to the LNS via an third interface, that supports bearer connectivity between the visited and home networks over die third interface; and a GGSN emulation module, coupled to the SGSN via a fourth interface, that supports bearer connectivity between the visited and home networks over the fourth interface by presenting a GGSN interface to the visited system and presenting a normal routing interface to the CDMA 2000 packet data system to thereby provide a packet routing function between the GGSN interface and the home system. WO 2005/057980 PCT/US2004/040430 36 51. A system according to claim 50, wherein the interface serves as an endpoint for a GTP tunnel and an IPSec tunnel. 52. A system according to claim 51, wherein the interface further comprises: an AAA emulation module, coupled to the AAA entity via an fifth interface, that provides an accounting function by interacting with the home network's AAA for L2TP authentication and 3GPP2 packet data accounting over the fifth interface. 53. A system in which a GPRS native subscriber using Mobile IPv4 roams to a visited CDMA 2000 packet data system that comprises an ANSI-41 visited location register, an AAA entity, and a packet data serving node/ foreign agent, comprising: a home GPRS system comprising a GSM home location register, a GGSN, and an AAA entity; and an interface entity mat couples the home system to the visited system, wherein the interface entity enables communication between the home system and the visited system. 54. A system according to claim 53, wherein the Interface entity further comprises: a home agent emulation module, coupled to the packet data serving node/ foreign agent via an first interface, that presents a home agent interface to the visited system; and a SGSN emulation module, coupled to the GGSN via a second interface, that presents a SGSN interface to the home system to support bearer connectivity between the visited and home networks by providing a packet routing function between the SGSN interface and the home agent interface. 55. A system according to claim 54, wherein the interface entity serves as an endpoint for a GTP tunnel and a Mobile IP tunnel. 56. A system according to claim 54, wherein the interface entity further comprises: WO 2005/057980 36 PCT/US2004/040430 a ANSI-41 home location register emulation module, coupled to the ANSI-41 visited location register via a third interface,; and a GSM visited location register emulation module, coupled to the GSM home location register via a third interface, to allow a subscriber to register; 57. A system according to claim 56, wherein the interface entity further comprises: a AAA emulation module, coupled to the AAA entity via a fourth interface and coupled to the AAA entity via a fifth interface, that interacts with: the visited network's AAA for Mobile IP authentication and 3GPP2 packet data accounting, over the fifth interface, and the home network's AAA for 3GPP packet data accounting, over the fourth interface. 58. A system in which a GPRS native subscriber using Simple IP roams to a visited CDMA 2000 packet data system tint comprises a ANSI-41 visited location register, a AAA entity, and a PDSN/LAC entity, comprising: a borne GPRS system comprising a GSM home location register, a GGSN, and an AAA entity; and an interface entity that couples the home system to the visited system, wherein the interface entity enables communication between the home system and the visited system. 59. A system according to claim 58, wherein the interface entity supports bearer connectivity between the visited and home networks by providing a packet routing function. 60. A system according to claim 59, wherein the interface entity further comprises: a SGSN emulation module, coupled to the GGSN over a first interface, that presents a SGSN interface to the home system; and WO 2005/057980 37 PCT/US2004/040430 a LNS emulation module, coupled to the packet data serving node/ LAC entity over an second interface, that presents a L2TP Network Server (LNS) interface to the visited system, wherein the interface provides the packet routing function between the SGSN emulation module and the LNS emulation module. 61. A system according to claim 60, wherein the interface entity serves as an endpoint for a GTP tunnel and a Mobile L2TP tunnel. 62. A system according to claim 61, wherein the interface entity further comprises: a ANSI-41 home location register emulation module, coupled to the ANSI-41 visited location register via a third interface, that allows a subscriber to register; and a GSM visited location register emulation module, coupled to the GSM home location register via another third interface, that allows me subscriber to register. 63. A system according to claim 62, wherein the interface entity further comprises: an AAA emulation module, coupled to the AAA entity via a fourth interface and coupled to the AAA entity via a fifth interface, that interacts with: the visited network's AAA entity, over an fifth interface, for L2TP authentication and 3GPP2 packet data accounting, and the home network's AAA entity, over an sixth interface, for 3GPP packet data accounting. 64. An interface entity that enables communication between a home CDMA 2000 packet data system and a visited GPRS system comprising a SGSN, when a CDMA 2000 packet data native subscriber using Mobile IPv4 roams to a visited GPRS system. 65. An interface entity according to claim 64, wherein the home CDMA 2000 packet data interface entity comprises a ANSI-41 home location register, an AAA entity, and a home agent, and wherein the interface entity further comprises: WO 2005/057980 39 PCT/US2004/040430 a GSM home location register emulation module, coupled to the SGSN via a first interface, that allows a subscriber to register over a first interface; and an ANSI-41 visited location register emulation module, coupled to the ANSI-41 home location register via a second interface, that allows a subscriber to register over the second interface. 66. An interface entity according to claim 64, wherein the interface entity further comprises: a foreign agent emulation module, coupled to the home agent via an third interface, that supports bearer connectivity between the visited interface entity and the home interface entity such mat a foreign agent interface and an AAA interface are presented to the CDMA 2000 packet data interface entity over the third interface; and a GGSN emulation module, coupled to the SGSN via a fourth interface, that supports bearer connectivity between the visited interface and the home interface entity such that a GGSN interface is presented to the visited interface entity over the fourth interface. 67. An interface entity according to claim 66, wherein the interface entity serves as an endpoint for a GTP tunnel and a Mobile IP tunnel. 68. An interface entity according to claim 67, wherein the interface entity provides a packet routing function between the GGSN interface and the foreign agent interface. 69. An interface entity according to claim 64, wherein the interface entity further comprises: an AAA emulation module, coupled to the AAA entity via an fifth interface, that provides an accounting function by to interacting with a home network's AAA for Mobile IP Foreign Agent challenge authentication and 3GPP2 packet data accounting. 70. An interface entity that enables communication between a home CDMA 2000 packet data system and a visited GPRS system comprising a SGSN, when a WO 2005/057980 40 PCT/US2004/04043© CDMA 2000 packet data native subscriber using Simple IP roams to a visited GPRS system. 71. An interface entity according to claim 70, wherein the home CDMA 2000 packet data system comprises a ANSI-41 home location register, an AAA entity, and a LNS, and wherein the interface entity further comprises: an ANSI-41 visited location register, coupled to the ANSI-41 home location register via a first interface, that allows a subscriber to register over the first interface; and a GSM home location register, coupled to the SGSN via a second interface, that allows a subscriber to register over the second interface. 72. An interface entity according to claim 71, wherein the interface entity further comprises: a LAC emulation module, coupled to the LNS via an third interface, that supports bearer connectivity between the visited and home networks over the fluid interface; and a GGSN emulation module, coupled to the SGSN via a fourth interface, that supports bearer connectivity between the visited and home networks over the fourth interface by presenting a GGSN interface to the visited system and presenting a normal routing interface to the CDMA 2000 packet data system to thereby provide a packet routing function between the GGSN interface and the home system. 73. An interface entity according to claim 72, wherein the interface entity serves as an endpoint for a GTP tunnel and an IPSec tunnel. 74. An interface entity according to claim 73, wherein the interface entity further comprises: an AAA emulation module, coupled to the AAA entity via an fifth interface, that provides an accounting function by interacting with the home network's AAA for L2TP authentication and 3GPP2 packet data accounting over the fifth interface. WO 2005/05798© 41 PCT/US2004/040430 75. An interface entity mat enables communication between a home GPRS system comprising a GSM home location register, a GGSN, and an AAA entity, and a visited CDMA 2000 packet data system mat comprises an ANSI-41 visited location register, an AAA entity, and a packet data serving node/ foreign agent, when a GPRS native subscriber using Mobile IPv4 roams to the visited CDMA 2000 packet data system. 76. An interface entity according to claim 75, wherein the interface entity further comprises: a home agent emulation module, coupled to the packet data serving node/ foreign agent via an first interface, that presents a home agent interface to the visited system; and a SGSN emulation module, coupled to the GGSN via a second interface, that presents a SGSN interface to the home system to support bearer connectivity between the visited and home networks by providing a packet routing function between the SGSN interface and the home agent interface. 77. An interface entity according to claim 76, wherein the interface entity serves as an endpoint for aGTP turmel and a Mobile IP tunnel. 78. An interface entity according to claim 76, wherein the interface entity further comprises: a ANSI-41 home location register emulation module, coupled to the ANSI-41 visited location register via a third interface; and a GSM visited location register emulation module, coupled to the GSM home location register via a third interface, to allow a subscriber to register; 79. An interface entity according to claim 78, wherein the interface entity further comprises: a AAA emulation module, coupled to the AAA entity via a fourth interface and coupled to the AAA entity via a fifth interface, that interacts with: the visited network's AAA for Mobile IP authentication and 3GPP2 packet data accounting, over the fifth interface, and WO 2005/057980 42 PCIYUS2004/04043© the home network's AAA for 3GPP packet data accounting, over the fourth interface. 80. An interface entity mat enables communication between a home GPRS system comprising a GSM home location register, a GGSN, and an AAA entity, and a visited CDMA 2000 packet data system mat comprises an ANSI-41 visited location register, an AAA entity, and a packet data serving node/LAC entity, when a GPRS native subscriber using Simple IP roams to the visited CDMA 2000 packet data system. 81. An interface entity according to claim 80, wherein the interface entity supports bearer connectivity between the visited and home networks by providing a packet routing function. 82. An interface entity according to claim 81, where in the interface entity further comprises: a SGSN emulation module, coupled to the GGSN over a first interface, mat presents a SGSN interface to the home system; and a INS emulation module, coupled to the packet data serving node/LAC entity over an second interface, mat presents a L2TP Network Server (LNS) interface to 1he visited system, wherein the interface provides the packet routing function between the SGSN emulation module and the LNS emulation module. 83. An interface entity according to claim 82, wherein the interface entity serves as an endpoint for a GTP tunnel and a Mobile L2TP tunnel. 84. An interface entity according to claim 83, wherein the interface entity further comprises: a ANSI-41 home location register emulation module, coupled to the ANSI-41 visited location register via a third interface, that allows a subscriber to register; and a GSM visited location register emulation module, coupled to the GSM home location register via another third interface, that allows the subscriber to register. WO 2005/057980 43 PCT/US2004/040430 85. An interface entity according to claim 84, wherein the interface entity further comprises: an AAA emulation module, coupled to the AAA entity via a fourth interface and coupled to the AAA entity via a fifth interface, that interacts with: the visited network's AAA entity, over an fifth interface, for L2TP authentication and 3GPP2 packet data accounting, and the home network's AAA entity, over an sixth interface, for 3GPP packet data accounting. 86. A method in which a CDMA 2000 packet data native subscriber using Mobile IPv4 roams from a home CDMA 2000 packet data system to a visited GPRS system, a system in which a CDMA 2000 packet data native subscriber using Mobile IPv4 roams to a visited GPRS system and an interface entity that enables communication between a home CDMA 2000 packet data system and a visited GPRS system substantially as herein described with reference to the accompanying drawings. Dated this 5th day of June 2006 OMAN A RAM AKRISHN AN Of K & S PARTNERS AGENT FOR THE APPLICANT(S) 44 ABSTRACT Interworking and interoperability function IIF architectures and corresponding call flows are provided for CDMA2000/GPRS roaming scenarios such as GPRS foreign mode with Mobile IPv4, GPRS foreign mode with Simple IPv4 or IPv6, CDMA2000 packet data foreign mode with Mobile IPv4, and CDMA2000 packet data foreign mode with Simple IPv4 or IPv6.

Documents:

654-MUMNP-2006-ABSTRACT(4-5-2012).pdf

654-mumnp-2006-abstract.doc

654-mumnp-2006-abstract.pdf

654-mumnp-2006-claims'.pdf

654-mumnp-2006-claims(6-6-2006).pdf

654-MUMNP-2006-CLAIMS(AMENDED)-(21-6-2012).pdf

654-MUMNP-2006-CLAIMS(AMENDED)-(4-5-2012).pdf

654-MUMNP-2006-CLAIMS(MARKED COPY)-(21-6-2012).pdf

654-MUMNP-2006-CLAIMS(MARKED COPY)-(4-5-2012).pdf

654-mumnp-2006-claims.doc

654-mumnp-2006-correspondance-received-ver-050606.pdf

654-mumnp-2006-correspondance-received-ver-240706.pdf

654-mumnp-2006-correspondence(27-11-2007).pdf

654-MUMNP-2006-CORRESPONDENCE(9-12-2011).pdf

654-mumnp-2006-description (complete).pdf

654-mumnp-2006-description(complete)-(6-6-2006).pdf

654-MUMNP-2006-DRAWING(4-5-2012).pdf

654-mumnp-2006-drawing(6-6-2006).pdf

654-mumnp-2006-drawings.pdf

654-MUMNP-2006-EP DOCUMENT(4-5-2012).pdf

654-MUMNP-2006-FORM 1(4-5-2012).pdf

654-mumnp-2006-form 18(27-11-2007).pdf

654-mumnp-2006-form 2(complete)-(6-6-2006).pdf

654-mumnp-2006-form 2(title page)-(6-6-2006).pdf

654-MUMNP-2006-FORM 26(4-5-2012).pdf

654-mumnp-2006-form 3(17-11-2006).pdf

654-MUMNP-2006-FORM 3(4-5-2012).pdf

654-MUMNP-2006-FORM 3(9-12-2011).pdf

654-mumnp-2006-form-1.pdf

654-mumnp-2006-form-2.doc

654-mumnp-2006-form-2.pdf

654-mumnp-2006-form-26.pdf

654-mumnp-2006-form-3.pdf

654-mumnp-2006-form-5.pdf

654-mumnp-2006-general power of attorney(6-6-2006).pdf

654-MUMNP-2006-PETITION UNDER RULE 137(4-5-2012).pdf

654-MUMNP-2006-REPLY TO EXAMINATION REPORT(4-5-2012).pdf

654-MUMNP-2006-REPLY TO HEARING(21-6-2012).pdf

654-MUMNP-2006-US DOCUMENT(4-5-2012).pdf

654-mumnp-2006-wo international publication report(6-6-2006).pdf

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